Method of recording and reproducing wave frequencies



0st. 20, 1931. R B, T KlLlANl 1,828,189

METHOD OF RECORDING AND BIZ-PRODUCING WAVE FREQUENCIES Filed June 18. 19.30 2 Sheets-Sheet 1 I l |Q IN V EN TOR.

ATTORNEY Oct. 20, 1931. R B K|L|AN| 1,828,189

METHOD OF RECORDING AND REPRODUCING WAVE FREQUENCIES Filed June 18, 1930 2 Sheets-Sheet 2 INVENTOR. '1 9 Z ATTORNEY Patented Oct. 20, 1931 UNITED STATES PATENT OFFICE RICHARD B. "I'. KILIAN'I, OF DETROIT, MICHIGAN, ASSIGNOR OF ONE-FOURTH TO ARTHUR GARDNER, OF DETROIT, MICHIGAN I METHOD or anconnme AND REPRODUCING wAvE rmioumroms Application filed Jun-e 18, 1930. Serial No. 462,068.

My invention relates to a new and improved method for recording and reproducing wave frequencies.

A method for'electro-magnetically recording telephone or telegraph signals was invented by Valdemar Poulson in 1898, but with the method described and used by him, and as improved upon from time to time by himself and by others, it is impossible to satisfactorily record and reproduce speech or music which will compare in quality with even the poorest type of modern honograph. This is due to the fact that t e frequencies present in speech and music,- as harm monies or overtones, vary between some cycles per second and 16,000 to 18,000 per second, and with his method the lower, and especially the higher frequencies, cannot be efiiciently recorded and retained on the magnetizable body used for recording, whether this be a steel wire, tape, disc, cylinder, or other physical shape of magnetizable material.

My invention contemplates a method for recording and reproducing any desired range of wave frequencies, whether it be in the audio-frequency range above mentioned, or above this limit, and which cantherefore be used for the recordingapd.reproduction of audible sounds in their true acoustical rela- 311 tion, as well as for recording and reproducing variationsin electric current of much 8 higher frequency, such as are present, for nstance, in the transmission of amoving ploture by means of television apparatus.

d5 netic record made by the methods followed 7 prior to my invention, a background of ru sh ing sound has been apparent in the reproduced speech or music, similar in character I to the needle scratch in reproduction from a phonograph, which objectionable feature may be termed wire scratch. This wire scratch arises from two sources :First, it is introduced atthetimeof making the electr o-magnetic record on I the magnetizable body, and, second, 1t 1s agaln produced when reproducing the electro-magnetic record by the means known and used for this purpose prior to the present invention.

to In following, my method for making a In thereproduction from an electro-magcopy of a phonograph record on a magnetizable body, for instance, the electro-magnetic reproduction of such a copy is clearer and more natural than the reproduction from the orlginal phonograph record by means of an acoustica reproducer; such electro-magnetic reproduction is also of such a tonal quality that it cannot be distinguished from an else-- tric reproduction from the original phonograph record.

If, however, an electro-magnetic record be made on a magnetizable body under my invention, using as the ori inal which is to be recorded, an orchestra, or example, the reproduction of such electro-magnetic record 5' will be better than an electric reproduction of a phonograph record, due to the fact that the above-mentioned needle scratch is present in the reproduction from the phonograph,

thus introducing an undesirable sound which was absent in the music of the original orchestra. In the reproduction from the electromagnetic record made and reproduced according to my invention, wire scratch is absent and the music as re roduced is an exact duplicate of that played by the orchestra, without'the addition or subtraction of any frequencies contained in the original music.

Having outlined some of the advantages and novel features of the present invention, 30 and what can be accomplished by its use, I will now state generally the means that may be employed in the practice of my invention, to accomplish the desired results.

A microphone or telephone transmitter is used to change sound waves in the air into corresponding electric waves in the wires leading from it; similarly, a photo-electric cell is used to transform light waves emanating from an object or picture into electric waves in-the wires leading from the photoelectric cell. These electric waves must then be recorded on a magnetizable body, without changing their form, amplitude, or character in any way, and without adding anything to or subtracting anything from them, smce any change whatsoever will result in an incorrect copy of the original sound or picture.

In the same way, when reproducing a rec- 0rd so made on a magnetizable body, electric ,waves must be produced which are an exact copy or reproduction of the original electric waves coming from the microphone or photoelectric cell, which electric waves are again changed into sound or light waves by a suitable device, such as a loud speaker, etc., to render them audible or visible as an exact copy of the original sound waves or light waves.

Any suitable means may be used to transform sound or light waves into corresponding electrical waves, and these electrical waves may be amplified to whatever degree is desired, by means of a suitable amplifier. These electrical waves are then made to energize a system of electro-magnets, setting up a series of magnetic fluctuations in the cores of the electro-magnets, which correspond to the original sound or light waves. These magnetic fluctuations in the above-mentioned cores are impressed on a magnetizable body which is caused to IHOXQ past the cores, with the result that the magnetic condition of the magnetizable body is altered to correspond to the original sound or light waves.

In the accompanying drawings:

Fig. 1 is a diagrammatic view of means for racticing the method of my invention, and illustrating an apparatus for recording magnetic impulses upon a magnetizable body;

Figs. 2, 3 and 4 are diagrammatic views of a portion of Fig. 1, illustrating modified forms of apparatus;

Fig. 5 is a diagrammatic view of an apparatus employed for reproducing the magnetic record from the magnetizable body;

Fig. 6 is a view similar to Figs. 1 and 5, illustrating the combined recording and reproducin circuits in operative relation with a magrf gzable body,

Fig. 7/ is a diagrammatic view taken at right angles to the view of Fig. 6, showing an arrangement of apparatus that may be employed for simultaneously recording and reproducing; and

Fig. 8 is a diagrammatic view of means for translating the magnetizahle body in operative relationship with respect to a magnetic circuit.

Referring to the drawings, and more particularly to Fig. 1, the recording apparatus illustrated includes a transmitting circuit comprising a microphone a and a battery 2. connected in series with the input side 3311 of a transformer or suitable amplifier 3. When it is desired to record light waves instead of sound waves, a photo-electric cell, not shown, may be employed in place of the microphone 2.

The recording or magnetic circuit is also a series circuit connected with the output side 30 of the transformer or suitable amplifier 3, and includes a plurality of electro-magnets 4 and 5, said magnets being spacedapart and arranged to contact lightly with the magnetizable body or wire 6 passing therebetween. The body 6 is subjected to magnets of difi'erent magnetic effect, and in the case illustrated, due to the series windings of the magnets 4 and 5, the magnetiz able body is subjected to opposite polarities during its translation between the effective areas of the magnets.

In the form of Fig. 1, the flux densities of the magnets 4 and 5 are equal, but obviously the same may be made unequal when desired. To this end, in Fig. 2, I have shown the magnet 4a of smaller cross-section than the magnet 5, both magnets having the same number of magnetic turns and the same current passing through both, thereby producing unequal flux density.

Similarly, in Fig. 3, the same result is produced by providing the electro-magnet 5a with a greater number of magnetic turns than the magnet 4 And, further, in Fig. 4, a resistance R is placed in circuit with the magnet 51), thereby dividing the total current in such a manner that only a portion thereof will pass through the magnetic windings of said magnet, thereby reducing the flux density therein.

In producing a record upon the magnetizable body 6, said body is translated by suitable means hereinafter more fully described, between the magnets 4 and 5. As stated supra, the magnets are in light contact only with the body or wire to obviate wear on the effective surfaces of said magnets and eliminate the scratch produced in previous methods.

Sound waves are transformed by means of the microphone transmitting circuit into magnetic im ulses in the magnets 4 and 5, which impu ses are recorded on the magnetizable body 6 to form a continuous record of said sound waves. This record is capable of being reproduced or re-tra-nsformed into sound waves by means of a somewhat similar apparatus.

In the step of reproducing, and as shown in Fig. 5, the magnetizable body or wire 6 passes between spaced-apart electro-magnets 7 and 8, the magnetic windings of which are in series with the input side 92' of a transformer or suitable amplifier 9. Said magnets are preferably of opposite polarity and serve to convert the magnetic record or impulses on the body 6 into an electric current in the transformer or amplifier it In this instance, the electro-magnets 7 and 8 are not-in intimate relation, or preferably not even in light contact with the body 6, but are on the verge of contact therewith, thus preventing the objectionable scratching during the reproduction step.

The output side 90 of the transformer or amplifier 9 is in turn connected in series with a reproducer or loud speaker 10, whereby the electric currents produced in the transformer 9 are reproduced into sound waves corresponding in quality and frequency with the waves transmitted and recorded by means of the apparatus in Fig. 1.

The recording apparatus shown in Fig. 1, and the reproducing apparatus of Fig. 5, may

' be positioned adjacent one another, as in Fig.

cording electro-magnets 4c and 5c, and the reproducing electro-magnets and are arranged radially with respect to the magnetizable body 6. Said magnets 40 and 50 are connected as in Fig. 6 in a transmitting circuit, and magnets 70 and 80 in a reproducing circuit. Thus, the record may be applied to the body or wire 6 by means of the magnets 40 and 50 having any of the characteristics shown in Figs. 1 to 4. inclusive, and instan taneously reproduced by means of the magnets 70 and 80, preferably of opposite polarity. 1

Fig. 8 illustrates one form of means for translating the magnetizable body or wire in operative relation with respect to the mag netic circuits. C designates generally a magnetic circuit which may be either the recording or the reproducing circuit, or both. I

The magnetizable body is wound upon two reels A and B, said reels being selectively rotatable by means of a motor M through suitable means, as for example, the belt drives shown, which operate to drive said reels through clutches, not shown. In the specific case shown, the reel A is being driven to translate the body 6 in the direction from B to A in operative relation with respect to the magnets C. Reel B is not driven by the motor M in such case, but is braked by suitable friction' means, not shown,.to maintain the required-tension in the body 6. i

For the sakeof simplicity, the drawings show only two magnets for recording and two for reproducing, a wire as the magnetizable body, a microphone for recording sound, and a loud speaker for reproducing sound; but a plurality of magnets for recording and for reproducing, any desired form of magnetiz able body, any suitablemeans for changing waves of any range of frequencies into electrical waves, and any suitable means for changing electrical waves back into waves of any range of frequencies may be used, so that v the invention may be applicable to recording and reproducing waves of any range of frequencies, such as sound waves or llght waves, for example.

' the body.

The systemof magnets used for recording on a magnetizable body preferably consists of two or more electro-magnets, with a different flux density for each electro-magnet, for any instantaneous value of the energizing current. One or more of the cores of these electro-magnets are in light contact with the magnetizable body.

Any suitable. means may be employed to obtain a different flux density for each electromagnet, such as cores of different materials, windings with a different number of turns, windings in opposite directions, cores of unequal cross-section, different values of the energizing current, or any combination of the various variables which affect flux density. It is, however, of the utmost importance that one or more of the cores of these electro-magnets be in light contact with the magnetizable body, since if they are not in contact, the electro-magnetic record on the body will not be precise and clearly defined, but will be distorted, while, if they are in too intimate a contact, the objectionable wire scratch will be recorded on the magnetizable body and cannot be eliminated, except by means which will also remove certain frequencies which were present in the original matter recorded, thus resulting in a distorted reproduction.

According to the methods employed prior to my invention, for recording on a magnetizable body, the core of the recording magnet has always been in intimate. and close con tact with the body to such'a degree that a definite pressure exists between the core and As a result of this contact under pressure, a very definite friction exists between the core of the magnet and the body, as the latter is caused to move past the core, with the result that both the core and the body, are subjected to a mutual rubbing action, and to more or less wear. When retimate contact between wire and magnet core. the wire ismore. or less deformed or tends to be moved out of its straight line movement past the core. For this reason. a groove or recess is worn in the core, with the result that after a certain amount of use, the core must bereplaced by a new one.

The wireitself is also subjected to wear, with the result that its surface is slowly eroded and roughened, but what is more important, changes are set up which are made evident in the reproduction by the presence in such reproduction of wave frequencies which were not present in the original matter from which the record was made.

In the case of records made by the method disclosed in the present invention, the cores of the recording magnets are in light contact with the magnetizable body, that is. they are just barely in contact with it, and little or no pressure, and therefore friction, exists between them. As a result, there is. very slight wear of the magnet cores, their life is very long, and the wear of the magnetizable body is also reduced to a minimum, thus retaining a smooth surface as opposed to the roughened surface with other methods, and of most importance, the above-mentioned undesirable changes resulting in the addition of frequencies not present in the original matter, are avoided, thus resulting in a perfect record and reproduction.

The system of electro-magnets used for reproducing a record so made on a magnetizable body. consists of two or more magnets, in the windings of which currents of different instantaneous values are induced by the passage of any point of the magnet-izable body past the poles of the magnets. One or more of the cores of these electro-magnets are on the verge of contact with the magnetizable body. The desired effect of induced currents in the windings of the magnets which are of different instantaneous values may be obtained in a variety of ways, by using any combination of the variables mentioned in the case of the magnetic system used for recording. In this case, however, none of the cores of the electromagnets'may be in contact with the body.

The important point is that one or more of the cores of these magnets be on the verge of contact with the magnetizable body, since, if they are in contact, the undesirable wire scratch will appear in the reproduction, while if they are moved too far away from the magnetizable body, the reproduction will not be clear cut, but will be distorted.

The same system of magnets as used for recording, may also be used for later reproduction, after the operation of recording has been completed. In this case, it will be necessary to move the cores of the magnets from the recording position where they are in light contact with the magnetizable body, to a position in which they are ready for reproduction and are on the verge of contact with the body. This movement of the cores of the electromagnets may be accomplished by any suitable means, as for instance, a micrometer screw which moves either the magnets and their cores or the cores alone.

The systems of electro-magnets used for recording and for reproducing may be the same system, as described above, or two separate systems, as shown in Fig. 6. In the event that two separate systems are used, one for recording and the other for reproduction, these two systems may be similar or may be unlike. I have found that I can use one system for recording and can obtain a satisfactory reproduction by the use of this same system or a similar system, of course, changing the position of the cores as decribed, using a light contact with the magnetizable body for recording and moving the cores to a position where they are on the verge of contact with the body when reproducmg.

For reproduction of a record so made, I can also use a system of electro-magnets, which is not similar to that used for recording, and with which I can obtain a satisfactory reproduction, but with which it is impossible to make a satisfactory record on the magnetizable body.

A record made and reproduced by the methods described in the invention can be retained indefinitely on the magnetizable body and can be reproduced as often as desired, without any change in the character of the reproduction. I have reproduced records so made thousands of times and have found that they are still in perfect condition after such repeated reproduction, which simulated the effect of several years use in a short period of time. This ermanency of the record is impossible to achieve with other means for recording and reproduction which were known and used prior to this time.

I claim:

1. The method of recording and reproducing wave frequencies, which consists in first subjecting a magnetizable body to the action of a magnet connected to suitable means for varying the magnetization of the magnet in accordance with said wave frequencies and which is in light contact with the body, and then subjecting a magnet connected to suitable means for reproducing said wave fre' quencies and which is on the verge of contact with the body, to the action of the body.

2. The method of recording and reproducing wave frequencies, which consists in first subjecting a magnetizable body to the action of a plurality of magnetic poles of different flux densities, and then subjecting a plurality of magnetic poles, connected to suitable means for reproducing said wave frequencies and which are disposed on the verge of contact with said body, to the action of said body.

3. The method of recording and reproducing wave frequencies, which consists in first subjecting a magnetizable body to light contact with a plurality of magnetic poles of different flux densities connected to a common source of energizing current, and then subjecting a plurality of electro-magnetic poles, connected to suitable means for reproducing said wave frequencies and which are disposed on the verge of contact with said body, to the action of said body. i

4. The method of recording and reproducing wave frequencies. which consists in subjecting a magnetizable body to the action of an electro-magnet connected to suitable'means for varying the electric current flowing through the winding of the magnet in accordance with said wave frequencies and which is in light contact with said body for recording and simultaneously subjecting an electromagnet, connected to suitable means for reproducing said wave frequencies and which is on the verge of contact with said body, to

the action of said body for reproducing,

whereby to elfect a simultaneous recording and reproducing. 5 5. A step in the method of recording and reproducing wave frequencies, which consists in subjecting a magnetizable body to light contact with a plurality of magnetic poles of different flux densities connected to a common source of energizing current.

6. A step in the method of recording and reproducing wave frequencies, which consists in subjecting a magnetizable body to light contact with a plurality of magnetic poles of different flux densities for any instantaneous value of energizing current.

7. A step in the method of recording and reproducing wave frequencies, which consists 20 in subjecting a plurality of electro-magnet-ic poles which are on the verge of contact with a magnetizable body on which said Wave frequencies have been previously recorded, and in the windings of which electric currents of different instantaneous values are induced, to the action of said body.

8. The method of recording and reproducing wave frequencies, which consists in first subjecting a magnetizable body to light contact with a plurality of magnetic poles of different flux densities, and then subjecting a plurality of magnetic poles, connected to suitable meansfor reproducing said wave frequencies and which are disposed on the verge 35 gf gontact with the body, to the action of said 9. 'ihe method of recording and reproducing wave frequencies, which consists in first subjecting a magnetizable body to the action of a plurality of magnetic poles of different flux densities connected to a common source of energizing current, and then subjecting a plurality of electro-Inagnetic poles, connected to suitable means for reproducing said wave frequencies and which are disposed on the verge gf gontact with said body, to the action of the 10. A step in the method of recording and reproducing wave frequencies, which consists 50 in subjecting a magnetizable body to the ac-' 1 tion of a plurality of magnetic poles of dif ferent flux densities connected to suitable means for varying the magnetization of said poles in accordance with said wave fre- 55 quencies.

11. A step in the method of recording and reproducing wave frequencies, which consists in subjecting a plurality of electro-magnetic poles in the windings of which electric curso rents of different instantaneous values are induced, to the action of a magn-etizable body on which said wave frequencies have been previously recorded.

In testimony whereof I aflix my signature.

65 RICHARD B. T. KILIAN I. 

